It's called MusicChoice, where there are a few dozen channels that play music 24/7/365. Each channel hosts a different genre like rock, jazz, pop, 70s/80s/90s era, etc. And one of those channels is called Sounds of the Season, where they play themed music for whatever particular season it is at any given point throughout the year. Halloween music at Halloween time, Irish music during St. Patty's week, Patriotic music during 4th of July, etc. And of course, Christmas music at Christmas time.
And appropriately, it ends when that particular season is over. My surprise right now is that I've never seen the Holiday music run this long into January.
I don't know every cable provider that has it. I have Cox, and the MusicChoice channels are way up there in the 900s. So check whatever cable you have to see if you have them. Maybe someone else can chime in who has another cable provider that also has the MusicChoice channels. And if you do, find Sounds of the Season, and the Holiday music is still playing.